installed a new 6:1 head now a tapping noise

[Roxo]

I install snyders 6:1 head ( old one was cracked ). Started the engine and had a tapping noise. Checked valves and found a broken valve guide on #4 exhaust. Replaced all guides and springs. Lapped in #4 checked all clearances, ground #4 to specs. Still have the same tapping noise.

I thought maybe a exhaust leak, gasket looked like #4 and #3 were leaking.
Installed new intake and exhaust manifolds with new copper gasket. Still same tapping noise.

Ground out the Spark plugs. When Grounding out #3 the tapping stops.
Is this a bad wrist pin??
There was no tapping with the old head.

[Railcarmover]

If you replaced a stock head you increased compression pressure by 50%,you basically made a bigger hammer.Given the wear in your valve train I'm going to assume the rest of your engine is worn as well.Higher compression is the best thing you can do to a model a engine to increase power (that,and carburetion),provided its in good shape. Unfortunately you have to go back in and find the root cause of the noise.

[Roxo]

Originally Posted by Railcarmover

If you replaced a stock head you increased compression pressure by 50%,you basically made a bigger hammer.Given the wear in your valve train I'm going to assume the rest of your engine is worn as well.Higher compression is the best thing you can do to a model a engine to increase power (that,and carburetion),provided its in good shape. Unfortunately you have to go back in and find the root cause of the noise.

Yes I'm afraid what I might find. It's an older rebuilt motor, no idea what kind of mileage is on it since. It ran great with no out of ordinary noises. I thought it was very guite running. Now tick tick tick. the change in compression must have woke something up.

[BillLee/Chandler, TX]

Same symptoms, much the same diagnostic path. Ended up pulling the motor and disassembling. Found #3 piston scored from rings down. Fortunately no damage to cylinder wall.


Now pistons/rings and back together successfully.


Good luck.

[Roxo]

Originally Posted by BillLee/Chandler, TX

Same symptoms, much the same diagnostic path. Ended up pulling the motor and disassembling. Found #3 piston scored from rings down. Fortunately no damage to cylinder wall.


Now pistons/rings and back together successfully.


Good luck.

my cylinder walls where fine after pulling the head back off to do the valve work. I need to pull the oil pan and check things out. Thanks for letting me know what you found, I will check for that.

[Railcarmover]

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If you can save the babbitt its not too expensive to freshen it up.Going high compression is a slippery slope,hard to stop when you feel speed.. A mechanical advance distributor to avoid detonation,ping is murder on the center main bearing..a downdraft stromberg 97 or holley 94 provides the fuel the Zenith lacks..while your there,a B cam compliments both pretty good,and toss in a header for the added zip..60-65 horse,add a mitchell OD and you can drive on any road you want without annoying the prius behind you..

[old31]

Does it tick when the engine first starts up, then does it ease off after the engine warms up?

[Jim Brierley]

It's possible a piston is hitting the head or gasket.

[Chris Haynes]

I had a tick, tick, tick that turned to a huge knock. It was my center main. Little did i know that when you raise the compression you need to retard the amount of full advance.

[Roxo]

Originally Posted by old31

Does it tick when the engine first starts up, then does it ease off after the engine warms up?

Its starts at startup and continues even after it warms up. It will stop for a few seconds then starts back up again. But just for 2 or 3 seconds.

[Roxo]

Originally Posted by Jim Brierley

It's possible a piston is hitting the head or gasket.

Never thought of that. I did try both the graphite and the copper head Gaskets.

[Roxo]

My big concern is why when I ground out #3 spark plug does the tricking stop? would that be a wrist pin or center main? This started after replacing the head with snyders 6:1 head.

[The Master Cylinder]

Keeping an eye on this thread. A friend has a fresh engine that has a tapping sound also.Quite until the engine gets warm. We not had time to investigate as yet. He has a 5.5 Snyder head.

[Werner]

Hello Roxo,

It will stop for a few seconds then starts back up again. But just for 2 or 3 seconds.

This is typical for so-called "piston tilting". This happens when the piston has a little too much wear in the cylinder diameter. Too much running tolerance between piston and cylinder. It tilts transversely 90 degrees to the piston pin axis.

[The Master Cylinder]

Originally Posted by Werner

Hello Roxo,


This is typical for so-called "piston tilting". This happens when the piston has a little too much wear in the cylinder diameter. Too much running tolerance between piston and cylinder. It tilts transversely 90 degrees to the piston pin axis.

I believe what you are referring to is what we call Piston Slap.

[Tom Wesenberg]

I was also thinking it could be piston slap.

[KR500]

When individuals change heads, I wonder if they are giving any consideration to deck height. Know of an individual who had his engine rebuilt by a reputable engine rebuilder and after engine warmed up( which may have come from engine component expansion rates, experienced a tapping sound. It was found that the piston was tapping the underside of the head and shining it up a bit. If the deck height of a model A engine is unknown, which how many times has engine been decked? I could for see pistons playing tag with a head.

[Werner]

I think we mean the same thing. The piston clatters because it "tilts" diagonally against the cylinder wall with its pressure flank during the ignition cycle and then beats against the other cylinder wall during compression cycle.

[Roxo]

With piston slap in mind here is what I know so far without opening up the engine again. There were no signs of ware on the piston walls as far as the piston body sliding up and down the walls. But again this just started.
One thing I did notice is there is a ridge on the top edge, on just one side of the walls on at least 2 piston cylinders (drivers side). Other side of the walls are smooth. Engine has been rebuilt, .080 stamped on the heads. I believe it's got a lot of miles on the rebuild.
Once I get the truck back together I will drop the pan and inspect from the bottom. Right now I'm pretty much rebuilding the truck from top to bottom. At this point I need to find out if rebuilding the motor should be on my list of things to be done.

[Railcarmover]

Piston protrusion should be measured,the quench area should be .030 to .040 for ideal combustion.Factor the head gasket crush for correct dimension.I have a milled snyder 5.5 that I use with a zero protrusion engine,runs good..

[BillLee/Chandler, TX]

Roxo, if you haven't yet pulled the pan, how could you see the sides of the pistons? On my engine, with very similar symptoms as you described, nothing was apparent until I could remove the pistons from the cylinders. And you must pull the pan (at least) to do that.

[Werner]

Roxo wrote

One thing I did notice is there is a ridge on the top edge, on just one side of the walls on at least 2 piston cylinders (drivers side). Other side of the walls are smooth.

If you can feel with your fingertip a little stage/level on the load side of the cylinder bore at top dead center, it means that the cylinder is badly worn. Then you can also see well that the honed tracks are polished off. This is called "bore polishing". That looks nice, but it is very bad. The cylinder track must not be mirror-smooth!

[Roxo]

Originally Posted by BillLee/Chandler, TX

Roxo, if you haven't yet pulled the pan, how could you see the sides of the pistons? On my engine, with very similar symptoms as you described, nothing was apparent until I could remove the pistons from the cylinders. And you must pull the pan (at least) to do that.

Your right I have not inspected the pistons themselves yet. I seen no signs of anything on the cylinder walls as I replaced the head. That does not mean I won't find wear on the pistons. I'm hoping my parts come in today so I can put things back together so I can drop the oil pan in the next few days.
I'm finding the restoration on this truck is much older then I hoped it was. I got this truck for a very good price so rebuilding the engine will not hurt me to bad.

[Fred K-OR]

Not knowing what I am talking about, but if it has adjustable valves in it, does one or more of them need adjusting??? Additional compression may have activated this click.

[bdtutton]

I was thinking of putting a high compression head on my car, but now I am thinking that if it is not broke, don't fix it. I live in a rural area and people are forgiving of my slow acceleration and moderate cruising speeds. The extra power sounds like fun, but it also sounds like it puts a lot more strain on the engine. My biggest problem is that I don't have overdrive and I sometimes have to cruise 50 mph for extended periods when I take longer trips to other parts of the state. My rear main is starting to leak a bit, but the old girl runs smooth, does not burn any oil and seems happy.
I guess my question is....I like all the extra HP mods, but how much engine life to I lose?

[Railcarmover]

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Sensible upgrades to a good engine can extend engine life..Higher compression means a more efficient burn,leading to less carbon buildup and longer lasting rings.Mechanical advance distributors prevent inadvertent detonation,one of the main causes of main bearing failure.The model a ford is under carbureted,it starves for fuel,a single down draft,like a stromberg 97,matches the CFM flow of the A engine spot on.Its easy to dump thousands of dollars 'hopping up' a model a engine,it some of the most expensive horsepower you can buy. Getting the engine up to 70 hp or so isn't that expensive,nor that detrimental to the engine health.Building up to 120 hp,using overhead valve conversions,B engine blocks reworked and all the goodies can run in excess of 15k..

No performance upgrade will help a tired engine,other than to accelerate the wear.

[Werner]

Of course, it's not that easy!


Every engine power means more or less wear, never without. If the power is increased, so is the wear higher. But unfortunately not linear, but squared. (Multiplicator²).
Increasing the compression increases the efficiency of the fuel combustion. But at least two factors are very important for this:

Combustion pressure increases the combustion temperature in the combustion chamber.

Much more serious, however, is the higher load on the crankshaft and connecting rod bearings. This can easily be calculated on the surface of the piston head surface Pressure : cm² / inch² and the increase in compression and the working pressure.

Increasing from 4 to 5 bar / cm² gives about 50% more pressure on the sliding bearing surfaces.
Since the A motor has no pressure circulation lubrication, the crankshaft bearings are quickly at the limit and overloaded, the wear increases disproportionately!

If it was my engine, I would not make an increase in performance. A revised engine with modern bearing tolerance and optimized material pairing yes. But not with an aged engine with an unknown life.

[Railcarmover]

Babbit has been used in diesel engines developing up to 400psi compression pressure.Properly clearanced main bearings with gravity feed systems will stand the 50% increase in compression pressure,especially with modern engine oils shear and load additives.You have to insure the engine is assembled and machined correctly and be sensible in the upgrades.

Ford designed a head for police application in 1931,with a 25% increase in compression pressure,public demand led to it being sold by dealers. Weiand,Winfield and many others offered high compression heads to meet demand.The engine has proven to be robust enough to handle upgrading.

Countless model a owners today use high compression heads without issue,and enjoy the increase in performance.Its is that easy....

[30 Closed Cab PU]

Roxio - sorry if this thread is getting hijacked, the info is very interesting though.


bdbutton- I agree with Warner's last paragraph.


"If it was my engine, I would not make an increase in performance. A revised engine with modern bearing tolerance and optimized material pairing yes. But not with an aged engine with an unknown life."


Opinion from an armchair mechanic with little actual experience - after talking with a couple of engine builders and restorers I am a firm believer that fixing/upgrading things piecemeal is asking for issues. A system wears and is designed as a system, not as individual components. Updating/improving one part may show a weakness in another part of a system. Most I talked to did not want to, or would not do a valve job without completely rebuilding my motor. Their view was that they had to many jobs come back at them when doing partial jobs, resulting in dissatisfied customers even though the customers were forewarned.


Somewhere recently I read an article/post where someone had actually used a dyno and measured results of using different heads and carburetors. Wish I could find it.
His data showed improving carburetion clearly increased power more than higher compression heads. The data supports Railcarmovers post above. However again, doing so on a worn out motor may be asking for problems.


I will let others chime in if they agree or disagree since I have no 1st hand experience, and am just passing on what I have read, and passing on some info from professional mechanics.

[Railcarmover]

Dyno sheets? Piriano posted them up..

http://www.modelaparts.net/dynosheet...ynosheets.html

[johnneilson]

Dennis Piranio in Tx has done quite a bit of dyno work and published it

http://www.modelaparts.net/

IMHO, just slapping a HC head on any old motor is asking for trouble.
Without some idea of the bottom end condition you can be easily doubling the loading on the bearings (which are marginal at best). Also, there is a tendency to run the motor at higher speeds once the power output is increased. I will stop here.

Can it be done, sure, but be smart about it. John

[30 Closed Cab PU]

This is the info I saw, however thought I had seen a summary of the testing where the conclusion of the testing was to improve airflow/carburation, and there was more testing wanting to be performed. Maybe it is on the link, but can not seem to find it.

[steve s]

If you listen very closely you will hear a double-tap if it's a loose or slapping piston, as it changes direction at top of stroke.

[30 Closed Cab PU]

Originally Posted by 30 Closed Cab PU

This is the info I saw, however thought I had seen a summary of the testing where the conclusion of the testing was to improve airflow/carburation, and there was more testing wanting to be performed. Maybe it is on the link, but can not seem to find it.

So here is the info I saw from a previous post, may have confused what I thought about carburation improvements being best.


Post 18 is to the point, buts lots of views/info spread throughout this string.


https://www.fordbarn.com/forum/showt...head+test+data

[Railcarmover]

The best blend is an improvement in all areas,head,cam carb and exhaust..each area aides the effect of the other.

Good rules of thumb in my opinion,your views may vary..

keep compression at 7 to 1 or under

two updraft carbs better than one updraft carb,one downdraft carb better than two updraft carbs

the more cam lift the better,stock B at .319 measured lift,way better than stock A at .287 measured..B cam has a better profile as well.

Stock exhaust manifold breathes well,header breathes great...open..but you'll wake the dead,almost all the header gain is lost with a resonator.

mechanical advance distributor insures accurate timing at all rpm ranges,and avoid damaging 'ping' the killer of main bearings

[Roxo]

Originally Posted by steve s

If you listen very closely you will hear a double-tap if it's a loose or slapping piston, as it changes direction at top of stroke.

It's a single tap. I did listen for a double tap. I'm planning on digging deep into the engine next week after I get things put back together. Again I'm waiting on more parts.
I will let you guys know what I find.

[steve s]

Originally Posted by Roxo

It's a single tap. I did listen for a double tap. I'm planning on digging deep into the engine next week after I get things put back together. Again I'm waiting on more parts.
I will let you guys know what I find.

If noise started after head swap, digging "deep" may not be answer. Problem is probably "shallow". Head or gasket or plug hitting piston.

[bdtutton]

I keep hearing about the deadly ping that will ruin my bearings if I don't have a mechanical advance on my distributer. I retard my timing to start. I only advance it about half way when I am idling and running around town or climbing hills and I only pull it all the way down when I am running 40+MPH. Am I doing enough to avoid the ping that will ruin my bearings or should I just get a mechanical advance for my distributer?

[1931 flamingo]

Before you drop the pan, pull the head and have a look see.
Paul in CT

[30 Closed Cab PU]

Originally Posted by bdtutton

I keep hearing about the deadly ping that will ruin my bearings if I don't have a mechanical advance on my distributer. I retard my timing to start. I only advance it about half way when I am idling and running around town or climbing hills and I only pull it all the way down when I am running 40+MPH. Am I doing enough to avoid the ping that will ruin my bearings or should I just get a mechanical advance for my distributer?

Are you running a stock compression Head? If yes what you are doing is OK.

[Purdy Swoft]

Originally Posted by 30 Closed Cab PU

Are you running a stock compression Head? If yes what you are doing is OK.

The first post on this thread says that he changed to a Snyders six to one head . The original compression ratio was only four point twenty two to one .

[Railcarmover]

Ford incorporated all their findings regarding improvements to to the A engine with the B engine.Mechanical advance distributor was one of them,along with a larger crankshft journal and main bearing pressure lubrication.

At 4.2 to 1 the engine tolerates imprecise timing.Two things change with increasing compression.The engine has less tolerance for timing deviation and performs at its best at 1 degree per 100 rpm advance.You cant match that accurately by hand.The second is the hammer effect of 'ping' increases with higher compression. Stock A engine runs more effciently,high compression A's run more efficiently with mechanical advance distributor

[BILL WILLIAMSON]

SO, how is the ticking doing????? "Maybe" it was caused by the cylinders that had ridges on them?????
Bill Guessing

[ursus]

The original posting details the rebuilding of the oil pump and installation of a new high compression head. The block and head have threaded drillings, the latter for an NPT plug in the oil passage from the pump and the latter for a bolt to lock the distributor in place. Some have found that overtightening either will cause odd noises and vibrations in the engine. I would check on this before tearing into the engine.

[Railcarmover]

Ridges at the top of the cylinder bore indicate a worn engine.Dis assembly and inspection is the next step.
Given the costs invoved overhauling sooner than later is prudent

[Killerbee]

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I also just installed a Snyder’s 6:1 and have went through 3 head gaskets in the past two weeks also I am getting the tapping. My engine ran perfect before installing the head. My engine has been rebuilt .030 over. My timing is dead on. I think Snyder’s got a bad set of heads.

[Roxo]

Originally Posted by Killerbee

I also just installed a Snyder’s 6:1 and have went through 3 head gaskets in the past two weeks also I am getting the tapping. My engine ran perfect before installing the head. My engine has been rebuilt .030 over. My timing is dead on. I think Snyder’s got a bad set of heads. I plan on calling them again about this issue Monday.i think you should do the same.

Very interesting. I might just do that this morning. Right now I'm checking on pricing to get the long block rebuilt. I just got my truck back together last night and was planning on pulling the head and maybe put the old head back on to see if the tapping goes away. I don't know how many times or how much the block has been resurfaced. The tapping started immediately at startup.

[zzlegend]

Be interested in knowing if your pistons stick up above the deck a small amount. And if so, how much?

[Purdy Swoft]

Originally , the pistons usually protruded about thirty to thirty three thousants above deck height .

[zzlegend]

Thanks Purdy. I have seen them protrude some what but never measured one. Just wondering if his block has been decked and how high his would be. Inquiring minds.

[katy]

Put the head on loose w/out a gasket, crank it over slowly by hand and see in any of the pistons hit the head.

[Werner]

You can put kneading rubber putty on the pistons head.

[Purdy Swoft]

I haven't measured but have heard that the Felpro copper clad head gasket compresses to about seventy thousants .

[Railcarmover]

Snyder heads are relieved for piston clearance,roughly .060...compressed head gasket runs from.050 to .070,depending on style. The maximum piston protrusion I have seen is .040..given the variables,and maximum piston protrusion with that 6 to 1 head the quench (quench is the actual distance from piston crown to head) factor is around .090..ideal quench for maximum performance is .030 to .040..

The snyder 5.5 and 6 are relieved above the piston..the odds of his piston contacting the head is nil..now if he had a winfield,there might be an issue..

[Roxo]

Ok here is the latest on my engine noises and that tapping I have.
I think it is in the timing. One more thing I must add, I had tried the Nu-Rex timing system. Truck run the same with or without the Nu-Rex system. Right now I have it installed again.
I found by retarding the timing it ran better and quieter, so I retarded some more and it is 90% better. Now idles and once again sounds like a Model A. I have read with this head you did not have to advance the timing as far, but I had to severely retard it.
I will play with it some more today and maybe take the Nu-Rex system back out and try it that way so I have control of the advance. I can't believe the difference in the noise level of the engine now, it's quite like it was before. But still think I might hear that tapping lightly as I rev up the RPMs while driving.
Still using the old style points and the bushing are tight no extra play at all so I did not rebuild my distributor, just new rotor, body, cap and points.

[Railcarmover]

I would leave the phillips (nurex) advance mechanism and retard the spark by turning the distributor cam back.Having mechanical advance set correctly is better than manual spark control.Instead of timing by ear use a timing light.

Detonation will fool you,it sounds just like a mechanical failure.Buy a stethoscope,Harbor Freight has one cheap,they are very handy in pinpointing engine noise.

[ryanheacox]

Originally Posted by 30 Closed Cab PU

Are you running a stock compression Head? If yes what you are doing is OK.

I realize this thread is getting quite off topic... but, I would agree with a stock head what you're doing sounds good. With a 5.5 head I never pull the spark down more than halfway. Was told once that a good rule of thumb is to advance the spark at an idle until the engine stops speeding up and that's how far you ever want to advance it.

[30 Closed Cab PU]

Originally Posted by Railcarmover

I would leave the phillips (nurex) advance mechanism and retard the spark by turning the distributor cam back.Having mechanical advance set correctly is better than manual spark control.Instead of timing by ear use a timing light.

Detonation will fool you,it sounds just like a mechanical failure.Buy a stethoscope,Harbor Freight has one cheap,they are very handy in pinpointing engine noise.

A Stethoscope works great, or you can do the old trick of using a large screwdriver with handle end up against your ear. Not as good but also works.


I used the screwdriver trick to track down a horrendous screeching noise which turned out to be a bad distributor bearing.

[Ernie Vitucci]

Good Afternoon...I have a friend who had this problem and he borrowed a stock head and put it on his older engine. He did not know how many miles were on the engine. With the stock head, the engine went back to running just fine and has for quite a while now. Just an idea. More compression stresses everything. If the engine has 'miles' on it...then it might well be happier with a stock head and you will have more money in your jeans! Ernie in Arizona!

[Roxo]

Originally Posted by Ernie Vitucci

Good Afternoon...I have a friend who had this problem and he borrowed a stock head and put it on his older engine. He did not know how many miles were on the engine. With the stock head, the engine went back to running just fine and has for quite a while now. Just an idea. More compression stresses everything. If the engine has 'miles' on it...then it might well be happier with a stock head and you will have more money in your jeans! Ernie in Arizona!

I do believe putting my old head back on is the way to go for now Ernie. The tapping started again today just as bad. Other then that it sounds great.
It is starting to look more like a wrist pin on number 2 or 3. If I idle it down as far I as can without stalling. I can hear a double tap. If I remember right that is usually a wrist pin.
I got gaskets coming in this week so I will remove the head, maybe the oil pan too. Check things out and go from there. Maybe the old head will get through the summer.
Sometimes it sucks to be me... LOL!

[Roxo]

My tapping noise was coming from the distributor hitting the Gasket. I did not expect that because the first time i did make sure to ream out the hole for the shaft. That's the part that puzzles me. The second time I got in a hurry and forgot to do that. I still herd a few light taps during a long time running. so I will inspect the distributor out further tomorrow. I did change out the upper shaft drilled for oiling. Maybe I missed something there also.

[Purdy Swoft]

Check to make sure that the rotor tip isn't striking some of the spark plug wire contacts in the distributor cap body , as the distributor shaft turns . Sometimes the plug wire contacts are too long and needs to be filed for clearance . I think that Ford listed a gap of twenty five thousants at the rotor tip . Check the gap with a feeler gauge at all four contacts . The gap needs to be the same on all four . A little more gap is OK if its not too much . I set mine at thirty five thousants for hotter spark at the spark plugs . When the spark jumps , it gets hotter . I've seen them so close that the distributor cap would slightly jump as the engine ran .

[denniskliesen]

Are you sure you dont have camshaft bounce? You can check for this by removing your timing pin, turning it around and if it has a rounded end hold it against the cam gear with engine at a slow idle. Apply pressure and most important know how far away that fan is from your hand. I have the tapping noise, camshaft bounce and am considering changing it out just to confirm its not a problem with the cam. I have regrind cam and new lifters to try.

[Roxo]

Originally Posted by denniskliesen

Are you sure you dont have camshaft bounce? You can check for this by removing your timing pin, turning it around and if it has a rounded end hold it against the cam gear with engine at a slow idle. Apply pressure and most important know how far away that fan is from your hand. I have the tapping noise, camshaft bounce and am considering changing it out just to confirm its not a problem with the cam. I have regrind cam and new lifters to try.

That's something I was meaning to check also. I will check that tomorrow morning. so far truck is running good.

[Roxo]

Originally Posted by Purdy Swoft

Check to make sure that the rotor tip isn't striking some of the spark plug wire contacts in the distributor cap body , as the distributor shaft turns . Sometimes the plug wire contacts are too long and needs to be filed for clearance . I think that Ford listed a gap of twenty five thousants at the rotor tip . Check the gap with a feeler gauge at all four contacts . The gap needs to be the same on all four . A little more gap is OK if its not too much . I set mine at thirty five thousants for hotter spark at the spark plugs . When the spark jumps , it gets hotter . I've seen them so close that the distributor cap would slightly jump as the engine ran .

I did check that this morning, it's one thing I did think of. Because it is a new cap I thought maybe it was hitting one of the contacts. Gap was good.

[30 Closed Cab PU]

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I do not know what type of noise happens, but I believe an overly tightened down screw for holding the distributor can make a noise. I am probably off base, but throwing it against the wall to see if it sticks.

[Roxo]

Originally Posted by 30 Closed Cab PU

I do not know what type of noise happens, but I believe an overly tightened down screw for holding the distributor can make a noise. I am probably off base, but throwing it against the wall to see if it sticks.

well I'm new to the Model A so that could be. I might just be over tightening the screw. I will check that too.